An ongoing goal in the electronics industry is to continue reducing the size of electronic devices, such as camcorders and cellular telephones, while increasing performance and speed. To accomplish this, increased miniaturization of integrated circuit (“IC”) packages for these devices is becoming increasingly essential. Personal data devices, notebook computers, portable music players, and digital cameras are but a few of the consumer products that require and benefit from this ongoing miniaturization of sophisticated electronics.
IC packages for complex electronic systems typically have a large number of interconnected IC chips, or dies. The IC dies are usually made from a semiconductor material such as silicon (Si) or gallium arsenide (GaAs). During manufacture, the several semiconductor devices on the IC dies are formed on the dies in various layers using photolithographic techniques. After manufacture, the IC dies are typically incorporated into packages that are then mounted on printed circuit boards.
IC die packages typically have numerous external pins, pads, or solder bumps that are mechanically attached, such as by soldering, to conductor patterns on the printed circuit boards. Typically, the packages in which these IC dies are mounted include a substrate or other die-mounting device. One example of such a substrate is a leadframe. High-performance leadframes typically include multi-layer structures having power, ground, and signal layers.
Leadframes also typically include an area on which an IC die is mounted and in which a number of power, ground, and/or signal leads is attached to the IC die. In particular, the power, ground, and/or signal leads of the leadframe are connected electrically to power, ground, and/or signal sites or pads on the IC die.
IC dies may be attached to the leadframe using adhesive or any other appropriate techniques for attaching such dies to a leadframe. Techniques commonly known to those skilled in the art for attaching such dies to a leadframe, for example, include soldering.
Once the IC dies are attached mechanically and electrically to the leadframe, the leadframe may be enclosed or encapsulated in a protective enclosure. Such enclosures may include encapsulation in a mold compound, such as plastic or epoxy, or in a multi-part housing made of plastic, ceramic, or metal. The enclosure may protect the leadframe and the attached die from physical, electrical, moisture, and/or chemical damage.
The leadframe and attached IC dies may then be mounted, for example, on a circuit board or circuit card along with other leadframes or devices. The circuit board or circuit card may then be incorporated into a wide variety of devices, such as computers, cellular telephones, automobiles, appliances, and so forth.
Typical known leadframes include a semiconductor die mounting structure, such as a die attach or mounting paddle. As technologies have improved and IC dies have become ever smaller, the leadframes for the chips, and the packages into which they are incorporated, have likewise become smaller and smaller. Modern semiconductor packaging is thus oriented toward small and thin semiconductor devices having high numbers of input and output pins.
Significantly, however, many of the older IC die designs and configurations are still popular and in use. Such IC dies continue to be manufactured, of course, in the larger configurations that were standard at the times of their designs. The packages in which such “mature” dies were originally incorporated can therefore be of substantial size by today's standards.
It would be beneficial to be able to use such mature IC dies in smaller contemporary package configurations, such as quad flat no lead (“QFN”) packages. Such smaller, contemporary packages, however, usually have correspondingly smaller internal leadframes that cannot properly accommodate larger, older, mature IC dies. Instead, it has been necessary to use older, larger leadframes in older, larger packages. This causes size, design, and cost penalties that can lead to additional customization costs because modern smaller dimensions and interconnect configurations cannot be used.
Thus, a need still remains for efficient, economical, and effective solutions to enable older-style, larger-footprint IC dies to be incorporated efficiently and effectively into the smaller and more compact packages that are in use today. In view of the ever-increasing need to save costs and improve efficiencies, it is more and more critical that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.